Field of the Invention
Example embodiments relate to a gas turbine apparatus, and more particularly, to a gas turbine apparatus which includes first and second turbine blades rotating in the opposite directions.
Description of the Related Art
In general, a gas turbine apparatus is a kind of turbo machine which directly applies high-temperature and high-pressure combustion gas to turbine blades and rotates a turbine to obtain power.
The gas turbine apparatus has a number of advantages. For example, the gas turbine apparatus can be reduced in size and weight, selectively use various types of fuels, and emit a small amount of pollutant. Thus, the gas turbine apparatus may be applied to various application fields.
FIG. 1 illustrates a conventional gas turbine apparatus 1. As illustrated in FIG. 1, the conventional gas turbine apparatus 1 basically includes a compressor 10, a combustor 20, and a turbine 30. The compressor 10 sucks and compresses external air, and transfers the compressed air to the combustor 20. The combustor 20 mixes the compressed air transferred from the compressor 10 with fuel, and then combusts the fuel mixture to generate high-temperature and high-pressure combustion gas. The turbine 30 expands the high-temperature and high-pressure combustion gas transferred from the combustor 20 through a turbine blade 32, and converts the expanded gas into a rotational force.
As illustrated in FIG. 2A, the turbine 30 of the gas turbine apparatus 1 includes turbine vanes 31 fixed to a casing 60 and turbine blades 32 connected to a driving shaft 40. The drive shaft 40 includes bearings 50 for rotatably supporting the driving shaft. The turbine vanes 31 and the turbine blades 32 are alternately arranged.
The turbine vane 31 serves to adjust a flow angle of the gas, which is combusted through the combustor and introduced into the turbine 30, and transfer the gas to the turbine blade 32, in a state where the turbine vane 31 is fixed to the casing 60. The turbine vane 31 is disposed between the respective turbine blades 32.
In order to adjust the flow angle of the introduced gas, the turbine vane 31 has a cross-sectional shape of which the central-axis line X-X′ is twisted at an angle with respect to the introduced combustion gas.
In general, the cross-sectional shape of the turbine vane 31 is implemented with a fixed blade, an airfoil, that is fixed to the casing 60. Thus, the following descriptions will be based on the turbine vane 31 as a fixed blade having the cross-sectional shape of the airfoil. The turbine blade 32 also has a similar cross-sectional shape, but corresponds to a rotor blade.
As illustrated in FIG. 2B which is a cross-sectional view taken along the central-axis direction X-X′, the combustion gas introduced into the turbine 30 from the combustor 20 has a flow direction (a) parallel to the central-axis line X-X′.
While most of velocity components of the introduced combustion gas are parallel to the central-axis line X-X′, the introduced combustion gas has almost no velocity components vertical to the central-axis line X-X′.
However, a flow (b) of the introduced combustion gas is twisted at an angle with respect to the central-axis line X-X′ by the turbine vane 31 provided at the entrance of the turbine 30.
That is, velocity components vertical to the central-axis line X-X′ are added by the turbine vane 31 at the entrance.
The combustion gas (b) having passed through the turbine vane 31 provided at the entrance of the turbine 30 enters the turbine blade 32 while having an angle of attack with respect to the turbine blade 32 disposed in succession to the turbine vane 31.
The turbine blade 32 having an airfoil shape is subjected to a lift force in a direction perpendicular to the central-axis line X-X′ by the combustion gas (b) having entered at the angle of attack. Then, the turbine blade 32 is rotated in a direction R indicated in the drawing.
The combustion gas (c) having passed the turbine blade 32 enters the next turbine vane 31 having an airfoil shape at an angle of attack. Then, the above-described process is repeated.
As described above, the turbine 30 of the conventional gas turbine apparatus 1 has a structure in which the turbine vanes 31 serving as fixed blades and the turbine blades 32 serving as rotor blades are alternately arranged.
Furthermore, as shown in FIG. 1, the compressor 10 similarly has compressor blades 11 and compressor vanes 12 alternately arranged.
The conventional gas turbine apparatus having the above-described structure has a problem in that it has a large volume and weight. Furthermore, the gas turbine apparatus has a large pressure loss therein, and such a pressure loss reduces the output of the turbine 30 and the entire efficiency of the gas turbine apparatus.